From cfd8951e082a589637f9de3c33efd3218fdb3c03 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Tue, 31 Aug 2010 14:06:22 -0700 Subject: xen: don't map missing memory When setting up a pte for a missing pfn (no matching mfn), just create an empty pte rather than a junk mapping. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/include/asm/xen/page.h | 9 ++++++++- arch/x86/xen/mmu.c | 15 ++++++++++++++- 2 files changed, 22 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index e40ca6e..875f5a0 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -41,10 +41,17 @@ extern bool set_phys_to_machine(unsigned long pfn, unsigned long mfn); static inline unsigned long pfn_to_mfn(unsigned long pfn) { + unsigned long mfn; + if (xen_feature(XENFEAT_auto_translated_physmap)) return pfn; - return get_phys_to_machine(pfn) & ~FOREIGN_FRAME_BIT; + mfn = get_phys_to_machine(pfn); + + if (mfn != INVALID_P2M_ENTRY) + mfn &= ~FOREIGN_FRAME_BIT; + + return mfn; } static inline int phys_to_machine_mapping_valid(unsigned long pfn) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 9b43bb3..4c63b7f 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -745,7 +745,20 @@ static pteval_t pte_pfn_to_mfn(pteval_t val) if (val & _PAGE_PRESENT) { unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; pteval_t flags = val & PTE_FLAGS_MASK; - val = ((pteval_t)pfn_to_mfn(pfn) << PAGE_SHIFT) | flags; + unsigned long mfn = pfn_to_mfn(pfn); + + /* + * If there's no mfn for the pfn, then just create an + * empty non-present pte. Unfortunately this loses + * information about the original pfn, so + * pte_mfn_to_pfn is asymmetric. + */ + if (unlikely(mfn == INVALID_P2M_ENTRY)) { + mfn = 0; + flags = 0; + } + + val = ((pteval_t)mfn << PAGE_SHIFT) | flags; } return val; -- cgit v1.1